1. Field of the Invention
The present invention relates to a process for producing an N-(hetero)aryl-substituted nitrogen-containing heteroaryl compound which is useful in the fields of medicines, agricultural chemicals, organic electroluminescent elements, catalyst ligands, solar cell elements, etc.
2. Description of the Related Art
N-(Hetero)aryl-substituted nitrogen-containing heteroaryl compounds are important intermediates for medicines and agricultural chemicals and are useful intermediates for organic electroluminescent elements, catalyst ligands, solar cell elements, and the like. Especially in the field of medicines, the compounds are exceedingly useful as intermediates for medicines for depression, cardiovascular diseases, inflammatory diseases, and other diseases (see International Publication No. 2003/104222, pamphlet, International Publication No. 2003/4027, pamphlet and European Patent No. 580502).
A known method for synthesizing an N-(hetero)aryl-substituted nitrogen-containing heteroaryl compound is a method of N—C bond formation by the Ullmann reaction employing a combination of a copper powder or copper salt and various ligands (see International Publication No. 2003/104222, pamphlet and Journal of the American Chemical Society, 2002, Vol. 124, No. 39, pp.11684-11688). However, this method has had drawbacks, for example, that impurities generate considerably due to the high-temperature reaction and a complicated purification operation is necessary for removing these impurities and that the reaction requires much time.
Another method which has been disclosed is a process for production in a homogeneous system employing a palladium catalyst and a phosphine ligand (see U.S. Patent Application Publication No. 2005054631 and Organic Letters, 2000, Vol. 2, pp. 1403-1406). However, this process has had drawbacks that since the catalyst is unstable in air, it is necessary to strictly remove oxygen from the reaction system and that the catalyst is difficult to recover/reuse, resulting in an exceedingly high production cost.